Motor controller equipment generally includes so-called "high voltage" motor contactors such as described within U.S. Pat. No. 3,198,910 entitled "Electromagnetic Relay Having Removable Contact and Coil Assemblies" as well as "low voltage" equipment in the form of relays and the like. One such relay being that described within U.S. Pat. No. 5,057,962 entitled "Microprocessor Based Protective Relay System".
The motor controller equipment is interlocked with the externally accessible handle operator to prevent access to the high voltage equipment when the operating handle is in the ON position. U.S. Pat. No. 4,760,220 entitled "Operator Mechanism Having Reduced Handle Throw and Improved Handle Lock" is one example of such an interlock.
The state of the art of such motor controller equipment is to mount the low voltage equipment in cabinets having a separate access door from that of the high voltage contactor within a separate compartment to allow ready access to the low voltage equipment without having to turn off the contactor. U.S. Pat. No. 3,621,339 entitled "Modular High Voltage Electrical Components Cooperating Within Cabinet Housing to Provide Electrical Insulation and Cooling Air Passage" describes the separate arrangement of the high voltage contactors and low voltage equipment.
It has been determined that emergency access to the high voltage contactors may be required while such contactors are in the ON condition and that the handle interlock arrangement should be defeated without damaging the equipment enclosure.
Accordingly, one purpose of the invention is to provide means for a skilled operator to access the high voltage contactor compartment under emergency conditions while the contactor is energized.